Reflow soldering is a process in which a solder paste is used to attach one or several electrical components to a substrate. Specifically, a solder paste is used to temporarily attach the electrical components to contact pads of the substrate, after which the assembly is subjected to controlled heat, which melts the solder and permanently connects the electrical components to the substrate. Reflow soldering is used to simultaneously couple several electrical components to a common substrate. Reflow soldering is generally a four-stage process that includes a preheat stage, a thermal soak stage, a reflow stage, and a cooling stage.
In known systems that are used for reflow soldering, the substrate assembly is formed from a substrate and electrical components temporarily coupled thereto with a solder paste. The substrate assembly is placed on a conveyor that passes through an oven that heats and cools the substrate assembly to achieve the reflow soldering necessary to attach the electrical components to the substrate. Such systems have generally been effective at achieving the necessary rapid cooling by transporting the substrate by the conveyor from a heated zone to a cooler zone thereby creating a temperature spike that controls important mechanical properties of the solidified solder. However, these prior art conveyor-type solder reflow systems suffer from many deficiencies, including high expense due to: (1) the need for many robots or personnel to operate the system; and (2) the need for a high flow rate of Nitrogen to maintain the relatively low oxygen content in the conveyor oven ambient atmosphere because the conveyor oven must be open on both ends. Furthermore, the conveyorized oven generates particulate material due to the motion between the belt and the oven floor, thus requiring that the conveyorized oven be located in a “dirty” environment, which necessitates back-and-forth movement of the substrate between the conveyorized oven to a clean area of the semiconductor facility
Thus, a need exists for a reflow soldering system and method that overcomes the deficiencies in the prior art. Specifically, a need exists for a low-cost alternative to the reflow soldering systems that are currently available that reduces cost, equipment footprint, and complexity.